Projecting apparatus for moving-picture machines



E. F. PORTER.

PROJECTING APPARATUS FOR MOVING PICTURE MACHINES.

APPLICATION FILED APR. 26. 1917.

1 356281 Patented M26, 192% 2 SHEETS-SHEET I E. F. PORTER,

PROJEQTiNG APPARATUS FOR MOVING PICTURE MACHINES. APPLICATION FILED APR.25. 1917.

5 ,7 7, Patentedl 0m. 26, 1920? 2 SHEETSSHEET Z.

fig. 5.

a W W UNITED STATES PATENT OFFICE. 1

EDWIN F. PORTER, 013. BOSTON, MASSACHUSETTS, ASSIGNOR T0 MOVING PICTUREAPPLIANCE CO., A CORPORATION OF MASSACHUSETTS.

PROJECTING APPARATUS FOR Application filed April 26,

To all 20 710m it may cmwer'n:

Be it known that I, EDWIN F. PoR'rnn, a siibect of the King of England,residing at Boston, in the county of Suffolk, Commonwealth ofMassachusetts, have invented a certain new and useful Improvement inProjecting Apparatus for Moving-Picture Machines, of which the followingis a specification.

My invention relates to that type of projecting apparatus for a movingplcture machine designed to provide a continuous series of projectedimages without interrupting the movement of the film strip orsuccessive-pictures to be reproduced and without interruptingillumination upon the screen. It has been my further object to produceamachine which shall be simple, inexpensive and easy of operation. Mydevice may be best understood by reference to the accompanying drawings,in which Figure 1 is a front view of those parts of my device lyingbehind the framing screen; Fig. 2 is a plan view; Fig. 3 is a side viewof certain parts of my device lying to the left of. the dotted line 33of Fig. 2, viewed in the direction of the arrow; Figs. 4;, 5 and 6 arediagrams, which will be hereinafter explained, illustrating the opticalprinciples and mode of operation of my invention.

Referring now more specifically to the drawings, A is a supporting framein which is journaled shaft B, which has fast thereon the operatingpulley b whiclris grooved to carry a belt. The film strip D is providedwith perforations in its edges, which perforations are adapted toregister with the teeth cor" the sprocket roller C in the usual man-'ner. A small idle roller 0 is journaled in the frame below the sprocketroller 0 for the purpose of supporting the film and holding it inengagement with the sprocket roller Across the end of projections a, aon frame A is mounted an aperture plate E provided with an aperture 6(indicated by dotted lines in Fig. 1). The shaft B has also fast thereonthe spiral gears F, F, which mesh with gears G, G, which are fast uponshafts g, gwhich are journaled in frame A at right angles to shaft B oneither side of the projections supporting the aper' ture plate. Thegears are arranged to rotate shafts g, g in the op osite directionsindicated by the arrows in ig. 1. Fixed fast to shaft 9 between flangesh, h is a circular Specification of Letters Patent.

of the usual objective.

MOVING-PICTURE MACHINES.

Patented Oct. 26, 1920.

1917. Serial No. 164,769.

glass disk I, the outer surface of which is flat and the inner surfaceof which is beveled toward the circumference so as to form four planeprisms 11 of equal angle and dimension, there being necessarily radialridges 2" between the prisms. Upon shaft 9 between flanges h k is asimilar glass disk I arranged to overlap disk I, its flat side beinginward so as to permit the disks to be in close juxtaposition when inmotion by the rotation of the respective shafts on which they aremounted. The disks I, I are so arranged upon their respective shaftsthat corresponding points upon the prismatic surfaces overlap eachother. The flanges h, h and 7%, h between which the disks I, I aresupported, are provided with set screws j which afford means ofadjustment of the position of disks I, I both in respect to each otherand in respect to proximity to .the objective. Mounted across an openingin frameA in 'alinement with the opening in the aperture plate E and inalinement with the overlapping parts of the disks I, I, is tube Jcarrying the rear lens (not shown) The front lens K of the objective ismounted within the annular rim is which is borne by the integral arm Lwhich is rotatably and slidably mounted by means of slot Z on rod Mwhich is rigidly supported on frame A. The opposite end of the arm L issupported by the arm Z which rests on the cam g which is fast ontherotatable shaft 9. A spring N, one end of which is fastened to rod M andthe other end of which bears loosely against a pin Z on the arm L exertsa constant force actuating arm L downward and outward toward cam gcausing the lug Z on the inside of arm L forming a cam shoe to bearagainst cam g which is fast on the end of the rotatable shaft g.

The operation of the machine is as follows: The film D moves downward bythe rotation of pprocket roller C upon the ro tating shaft due to theengagement of film perforations (not shown) with the sprocket teeth a,closely behind aperture plate E, the aperture of which is of the lengthof three or more (but preferably three) ictures on the film. The gearsF, F and Gr are so arranged as to rotate disks I, I in the oppicturethereon for each quarter revolution of the disks. The relation of thedisks to the film strip is so adjusted that when a di viding linebetween prisms qn one disk overlies a corresponding dividing llne on theother disk opposite the center of aperture 6,

a dividing line between film pictures is also opposite the center of theaperture 6 and opposite said dividing lines on said prisms.

It will be readily apparent that upon the revolution of disks 1, Ione-eighth of a turn into the position in Fig. 1,.the beam of light froma source of light passing through condenser X, as shown in Fig. t, willpass through the film and aperture in the aperture plate and through theobjectives between which the disks I'and I present parallel verticalfaces, and the film picture which by the movement of the'film has nowcome into central position in the aperture of the aperture plate and inrelation to the focal axis of the system will be reproduced as thecentral image of the three projected pictures and is thrown upon ascreen. The Ipictures above and below it may be obscured y the framingscreen 0 indicated in Fig. 3 which may be adjustably connected withframe A or otherwise independently supported and which has an aperturesufiicient to permit the display of the picture intended to berepresented on the screen while obscuring the images of the picturesabove and below. As the film moves downwardly the continued rotation ofthe disks 1, I will bring about a change in the relation of theirsurfaces presented to the beam of light, there appearingan angulardisposition of the outer surfaces of the disks which surfaces slantdownwardly and outwardly from the top thus producing arefracting'element of increasing power which counteracts or compensatesthe eifect of the downward movement of the film which would otherwiseresult in the upward movement of the projected image on the screen thusholding this image in place upon the screen. From the relation of themovement of the parts of the machine, it will be apparent that when thisfilm picture which was the central film picture has moved downwardlyabout a half of its width, a change occurs immediately in the prismaticform of that portion of the disks which is in the path of the beam oflight as the ridges of the disks approach alinement' presenting aprismatic form wherein the outer surfaces of the disks slant downwardlyand inwardly thus suddenly throwing up the image which has beenrepresented on the screen toa position where it may be obscured by theframing screen 0. There is immediately brought into view however uponthe screen an image which is reproduced from the film pictureimmediately above the film picture, the image of which was previouslyreproduced, the rays surfaces of the disks, which prismatic form.

instead of refracting the picture rays downward to an increasing degreenow has'the equally compensating effect of refracting them upward to acontinuously diminishing extent until the non-refracting position of thedisks shownin Fig. 1 and diagrammati cal Fig. 4 is reached and passedwhen the compensating eifect gradually becomes that of refractingdownward more and more as the film passes through the lower area of thebeam of light below the focal axis, from whichposition it wouldotherwise be reproduced higher upon the screen. I As this film picturenow being reproduced continues its downward movement, the light beampassing therethrough again encounters the sudden change of prismaticinfluence of the disks, and are thrown upward above the screen area asbefore while the picture beams of the picture above are cast upon thescreen.

Thus it willbc seen that in the cycle of operation of the device therays of light from a film picture in the upper part of a projectedbeamabove the focal axis of the system are projected upon the screen passingthrough a prism'that tends to throw them upward with ever diminishingpower, to compensate for the effect of film movement until the filmpicture is on the focal axis of the system when the revolving diskspresent an area which is non-refracting in the vertical plane and:thereafter the film picture .passes into the light beam below the focalaxis of the system and the beam of light passing therethrough encountersa gradually growing prism of opposite character which tends to refractthe beam downwardly to an increasingxdegree until suddenly the beamencounters a fully developed prism of changed character which throws thepicture beam up and off of the screen, and substitutes upon the screenthe image of the next succeeding film picture. It is apparent that ifthe image of the picture is to be kept upon the screen notwithstandingthe fact that the picture moves from above to below the focal axis ofthe system, it must'be influenced by opposite prismatic forms, the apexof one succeeding the apex of the other, the first prismatic formgradually collapsing until it disappears and the second prismatic formbegins to grow. But when it becomes necessary to suddenly deflect thepicture beam so as to throw its image off the screen and substitute thatof the picture above it, an abrupt change of prismatic influence isnecessary and this is afforded by the sudden appearance of a fullydeveloped prism of opposite character to that preceding it, occasionedby the passage through the beam of light of the radial ridges upon therevolving disks. 4

By reference to Fig. 5, it will be seen that the beam of light passingthrough the system in the position therein shown will be refractedupwardly to a point above the optical center of the outer objectivethrough which it is again refracted downwardly to its intended positionupon the screen. This slight vertical displacement ofthe beam of lightat the point occupied by the framing screen will cause the shadow of theedges of the aperture of the screen to fluctuate slightly upon the edgesof the picture screen and to eliminate the objectionable appearance ofthis shadow fluctuation, I prefer to make the edges of the picturescreen to be used with my device of a dark, light-absorbing material.

Inasmuch as screen distances vary and it becomes necessary to so adjustthe device that successive pictures will register upon the screen I haveprovided means for doing this by adjusting the location'of the prismaticdisks I, I by sliding them upon shafts g, g after loosening flanges h, hand 71?, h by unscrewing set screws j. It will be apparent fromexamination of. the diagram shown in Fig. 5 that the farther therotating disks are removed from the outer objective when in the positionshown in that figure, the higher the rays of light passing through thedisk will impinge above the optical center of the outer objective or thelower beneath it when the opposite prismatic form is in operation. Itwill be seen also that-the refraction of light by the objective iscounter to that of the prism formed by the disks thereby partiallynegativing the refraction. Therefore if the prisms presented by therevolving disks are too strong for a given screen distance their effectmay be weakened by moving them away from the outer objective or viceversa.

Although I have spoken of the com ensation of the movement of the filmby t e action of the revolving prismatic disks, it is not to beunderstood that I intend to represent that it is fully compensated as itis to be noted that the upward speed of the overlapping parts of therevolving disks, in the sense of vertical direction, is variable because of their circular movement, and the vertical speed is greatest atthe center of the beam of light and increases as that point isapproached and diminishes after that point is passed. Some means ofcompensation must be provided for this variability. The

effect of those elements of my device which I have already explainedwould be to reproduce upon the screen approximately steady picturesaffected by a slight, regular, vertical fluctuation. To correct this andto produce what is required in commercial reprois afforded by the end ofarm Z which is in rigid relation with objective K. It will be observedin Fig. 1 that the cam g has four throws the peaks of which are each soplaced in relation to a corresponding pg'ism of the rotary disk I thatthe objective is brought to its highest point of elevation shortlybefore the ridges of the disk pass into the beam of light therebycausing a change in its refraction. Hence assuming the device to bemoving from the position in which its parts are shown in Fig. 1, it willbe apparent that a slight movement will bring the objective to itshighest point and that it will then begin to drop as the rotating diskspresent to the beam of light a prism, the sides of which diverge as theyapproach the base, which prism upon the rotation of the disks is beingconstantly built up so that the angle of divergence of its sides isconstantly increasing, thus causing the rays from the film picture whichis being displayed to be moved downwardly at substantially the same ratethat they are moved upwardly by the downward motion of the film. Butthis compensation is not complete owing to the variation of speed in thegrowth of the prism, it growing more slowly toward its base as the disksrevolve due to the variation of speed at different points in the samevertical line. Hence the motion of the film which is traveling downwardat uniform speed tends, as it reaches a low position where the picturebeam is under the influence of the less rapidly growing influence of theprism, to cast the picture up on the screen to a degree which is notovercome by the action of the prism presented by the disks. Thusitbecomes necessary to move the outer objective K slightly downward, amotion which is at this time permitted by the cam 9 which mo tion issuch as to retain the picture in its place upon the screen as far asvertical displacement is concerned. It will be apparent that the actionof. the revolving disks, notwithstanding the fact that since theyoverlap one compensates for the lateral displacement of the beam oflight occasioned by the other, nevertheless jointly cause a varying iosIII

to the factthat the angle of the outer surfaces variesas the disksrevolve, thus causing diversity in their angular relation to the -lightrays, a feature which is illustrated diagraatically in Fig. 6 whichshows the ray ot light as it is retracted when the surfaces present anextreme angle as shown by solid lines, and a lesser angle as shown bydotted lines. To steady the picture on the screen against lateralfluctuation and compensate for this variation, I have provided the cam 9against which bears cam slioe Z on the inside of arm L. The efi'ect ofthis cam g is to move the arm L and the outer objective K borne therebyto the right, when viewed inthe position of Fig. 1 as a prism growingtoward its lower portion by the revolution of the disks is in effect inthe beam of light, thereby causing the outer surfaces of the disks inthe horizontal plane more nearly to a proach a parallel relation thustendin to t row the picture beam to the left, ane ect which iscompensated by the attendant movement at the outer objective K towardthe right. The exact shaping of cams-g 9 so as to effect a completesteadying ot the picture is tov some degree a matter of experimentalgrinding ot the cam surfaces while the machine is being operated at veryslow speed as slight detects or irre ularities in the construction ofthe disks I, or the parts whereon they are mounted may also require tobe compensated through the shaping of these cams. It will be understoodof course that the operation of the cams at times when the prismaticcondition presented by the revolution of the disks is the opposite fromthat above stated,-viz.,when they present to the beam of light a prism,the sides of which diverge toward the top is the reverse from that whichI have previously ex lained.

Althoug I have shown a construction in which the circular glass disksare provided with tour plane prisms nevertheless I do not wish to beunderstood to be limited to that number as it will be apparent that avarying number may be employed provided the construction of the motionimparting parts is such as to cause the stated relation of film picturemovement with disk movement whereby the disks rotate the'distance eatone of their plane prisms during the movement of the film strip a singlepicture distance. I

The compensating eflects aitorded by the movement of the outer objectiveK might of course also be obtained by moving the inner objective whileleaving the outer objective fixedly mounted but I have preterred to movethe outer objective as this is apparently the more simple and convenientmechanical operation. While I am aware that moving picture machines havebeen constructed in a manner whereby it has been sought to obtaincontinuous projection from a continuously moving film tuation ot thepicture beamor temporary obscurement thereot. With my device however, itis apparent that there is true, con

tinuous projection, there always being a picture upon the screen and noloss of light from the dimming of the picture. My device has the furtheradvantage of being both simple and cheap of construction and easy ofoperation.

Having thus fully described my invention, what I claim is: I

1. In a device of the character specified the combination of means forcontinuously moving a film strip, an objective, movable retractingmembers so shaped that when moved they may present to a beam of lightpassing through said film strip and said objective varying, successiveprismatic torms, each of opposite retracting character, one growing andincreasing in its power of refraction and the other diminishing anddecreasing in its power of retraction, the growing prismatic form beingtollowed abruptly by a prismatic torm fully developed and'ot oppositeretracting character which diminishes and is succeeded in turn by saidgrowing prismatic form, said retracting members vbeing adapted succes'sively to substitute upon a screen the images of successive filmpictures and retain said images upon said screen, each during the periodof its display, notwithstanding the movement of said film strip, meansfor compensating tor inadequacy of said retracting members to completelycounteract the effect of the. movement of said film strip, and means forpreventing the lateral fluctuation of images upon the screen due to thevarying lateral retraction of said retracting members at differentstages of their operation.

2. In a device of the character specified the combination of means forcontinuously moving a film strip, an objective, movable retractingmembers so shaped that when moved they may present to a beam of lightpassing through said film strip and said objective varying, successiveprismatic torms,

each of opposite retracting character, one

growing and increasing in its power of retraction and the otherdiminishing and decreasing in its power of retraction, the growinprismatic torm being followed abruptly y a prismatic form fullydeveloped and of opposite refracting character which diminishes and issucceeded in turn by said growing prismatic form, said retractingmembers being adapted successively to substitute upon a screen theimages of successive film pictures and retain said images upon saidscreen, each during the period of its display, notwithstanding themovement of said film strip, means for compensating for inadequacy ofsaid refracting members to completely counteract the effect of themovement of said film strip, means for preventing the lateralfluctuation of images upon the screen due to the varying lateralrefraction of said refracting members at different stages of theiroperation,-

and means for compensating for accidental refraction due toimperfections of construction of said movable refracting members or theparts whereby they are actuated.

3. In a device of the characterspecified the combination of meansaffording a passage for a beam of light, means for mounting a film stripacross said passage, a movably mounted objective arranged to influencethe beam of light passing through said film strip, a pair of shaftsrotatably mount ed one on each side of said objective, two glass disks,each affixed to one of said shafts in a manner whereby their peripheriesoverlap within said beam of light, said disks being beveled upon theirremote sides so as to form a uniform series of plane prisms, means forrotating said shafts in opposite directions and actuating said filmstrip in a manner whereby it may be moved the distance of a picturethereon while said disks are rotating a distance equal to one of theirplane prisms, a cam on one of said shafts and a cam shoe in connectionwith said objective, said cam being arranged to elevate and lower saidobjective.

4. In a device of the character specified. the combination of meansaffording a passage for a beam of light, means for mount ing a filmstrip across said passage, an objective arranged to influence the beamof light passing through said film strip, a pair of shafts rotatablymounted one on each side of said objective, two glass disks, eachaffixed to one of said shafts in a manner whereby their peripheries mayoverlap within said beam of light, said disks being beveled upon theirremote sides so as to form a uniform series of plane prisms, and meansfor rotating said shafts in opposite directions and actuating said filmstrip in a manner whereby it may be moved the distance of a picturethereon while said disks are rotating a distance equal to one of theirplane prisms, a cam mounted on one of said rotatable shafts, an armslidably supported whereon said objective is mounted, a lug on said armarranged to bear on said cam and a spring arranged to actuate said armso as to hold said arm in engagement with the cam, said cam beingarranged to give said arm and the objective carried thereby a lateralreciprocating movement.

5. In a device of the character specified the combination of meansaffording a pas sage for a beam of light, means for mounting a filmstrip across said passage, an objective arranged to influence the beamof light passing through said film strip, a pair of shafts rotatablymounted one on each side of said objective, two glass disks, eachafiixed to one of said shafts in a manner whereby their peripheries mayoverlap within said beam of light, said disks being beveled upon theirremote sides so as to form a uniform series of plane prisms, and meansfor rotating said shafts in opposite directions and actuating said filmstrip in a manner whereby it may be moved the distance of a picturethereon while said disks are rotating a distance equal to one of theirplane prisms, an arm slidably and rockably supported whereon saidobjective is mounted, cams on each of said shafts, members connectedwith said arm and arranged to bear upon said cams which cams arearranged to elevate and lower said arm whereon said objective is mountedand to give the same a lateral reciprocating move ment and a springarranged to actuate said arm so as to hold said members connectedtherewith in engagement with said cams.

6. In a device of the character specified the combination of means forprojecting an uninterrupted beam of light, means for continuously movinga film strip across said beam of light, a movably mounted objective,arranged to be moved in a plane transverse to said beam of light,movable refracting means for successively substituting upon a screen theimages of successive film pictures andretaining said images upon saidscreen each during the period of its display, notwithstanding themovement of said film strip and means for moving said objective.

In testimony whereof I have hereunto affixed my signature.

.EDW IN F. PORTER

